3 cups 100% pure maple syrup
1/4 tsp. cream of tartar
3 egg whites, beaten
3 tbsp. confectioners' sugar

Boil the maple syrup and 1/4 tsp. cream of tartar to 238F on a candy thermometer. Slowly drizzle the syrup into the beaten egg whites, continuing to beat until the syrup is all used and the egg whites hold peaks.

Beat in 3 tablespoons confectioners' sugar at the end. Beat until icing is of a good spreading consistency.